As tuition fees increase, universities need to be concerned whether costs have risen to a point where students from low-income families are being disproportionately excluded. Given the rates of increases in tuition fees in recent times, this outcome seems plausible and is often the opening point of discussions on this matter (see for example, the position of the Canadian Association of University Teachers, 2002, cited below). However, trends in university enrollments relative to trends in tuition fees would suggest otherwise. Consequently, we take as our starting point a review of what the existing studies have to say in this regard. We next review available data pertaining to the question of whether observed enrollment growth is attributable to increases in the proportion of high SES students. We found that the methodologies used and the time periods encompassed differ to an extent that the generalisability of the results necessarily need be constrained. The implication from our point of view is that we cannot be certain what the answer to the question would be for our University. Therefore, we devised a study using a novel methodology based on a national census data base and students' zip codes to develop indicators of socio-economic status for individual students. For reasons we elaborate on later in the paper, we restrict our attention to entering high school graduates (freshmen)--and to general arts and science bachelors programs. The study compares results from the University of Calgary freshmen cohorts of 1991 and 2002 to assess whether the socio-economic mix of the student body has changed and if this change might be due to increases in tuition fees. Our methodology has a number of advantages over the available alternatives. We do not need to rely on surveying students (with the attendant problems of cost, comprehensiveness and unreliability of student-reports of family circumstances). We are also able to use multiple indicators reflective of socio-economic status rather than relying on a single index. The results of our study indicate that the freshmen students in 2002 come from family circumstances that are (significantly) socio-economically better than those of the freshmen cohort entering in 1991 (which was prior to a period of substantial increases in tuition fees at the University of Calgary). (Contains 2 figures and 2 tables.)